1. Field of the Invention
The invention relates to methods, apparatus and systems for reducing the size of one or more spaces adjacent to a deformable component of a device. In one embodiment, for example, the invention relates to methods, apparatus and systems for discouraging the extrusion of one or more borehole sealing elements, or members, of a downhole tool into a gap formed between the tool and the borehole. The invention is particularly applicable to packers, including cup and tension set packers.
2. Description of Related Art
Various operations involve the use of devices having one or more deformable members that may undesirably move, or extrude, into a space adjacent to the deformable member. As used throughout this patent, the term “deformable member” means a component, part, or member that may deform under pressure. This often occurs, for example, with devices that are inserted into a borehole, wherein the deformable member is used to form a seal between the device and the borehole wall or other item(s). As used throughout this patent, the term “borehole” means a hole, passageway or area, such as, for example, a wellbore having a casing, within which a device having a deformable member may be deployed. To fit the device into the borehole, the outer width or diameter of the device is often smaller than the inner width or diameter of the borehole. After the device is positioned as desired in the borehole, the deformable member is extended from the device across the annulus formed between the device and the borehole wall, or other item(s), against which it will seal. In such instances, the deformable member may be undesirably forced or extruded into the open annulus adjacent to the deformable member, such as when subject to a differential pressure. Extrusion of the deformable member may not be desirable, such as when it causes the deformable member to become damaged or lose its seal.
This occurs, for example, in the petroleum exploration and recovery industries in operations involving the formation of seals around various types of tools and other equipment in subsurface wells. An example device having one or more deformable members that may be subject to undesirable extrusion is a packer. Packers are often used to secure the position of tubing or other equipment in a borehole, and to isolate the borehole above and below the packer to allow one or more treatment, or operation, to be conducted. A typical packer, which may, for example, be of the inflatable, cup, or tension set type, includes, among other components, one or more elastomeric members (the deformable member) that are extended across an annulus formed between the packer and the borehole wall to form a seal and isolate the borehole above and below itself.
Various solutions have been proposed to address the problem of undesirable extrusion of deformable members. Examples of proposed solutions for preventing or discouraging the extrusion of deformable members in packers and other devices in the petroleum exploration and recovery industries are disclosed in U.S. Pat. Nos. 6,167,963 B1; 6,102,117; 5,988,276; 5,904,354; 5,701,959; 5,603,511; and 5,924,696. These proposed solutions include the use of metal or phenolic pieces and/or garter springs embedded into the elastomeric member, a ceramic seat in which the elastomeric member is located, shoe-type supports held together by c-rings, and split rings or multiple slips. A complete review of each example patent will provide a thorough description of the disclosed design and indicate various limitations thereof.
Thus, there remains a need for methods, apparatus and/or systems for discouraging the undesirable extrusion of a deformable member having one or more of the following capabilities or features: reduces the width, or size, of the gap into which the deformable member may extrude; is removable from the borehole, resettable and reusable; is not deformable; does not hinder removal of the device from the borehole; does not leave substantial debris, or residual material, in the borehole that could obstruct removal of the device from the borehole; has a continuous, or unbroken, outer surface proximate to the deformable member; involves an anti-extrusion device that does not have openings into which the deformable member may extrude; does not significantly increase the length of the device with which it is used; is capable of providing forces upon the deformable member to assist in maintaining its position or seal; assists the deformable member to maintain an isolation seal in a borehole at significant differential pressures, such as, for example, greater than approximately 6000 psi, and high temperatures, such as greater than approximately 300° F.; assists in providing an isolation seal across a large gap in the borehole; assists in reducing the size of the gap sufficient to increase the pressure rating of the device; does not require an expensive rubber embedding process for its manufacture or assembly; and does not rely upon the bonding of rubber for its manufacture or assembly.